U.S. patent application number 13/558161 was filed with the patent office on 2014-01-30 for exhaust diffuser for a gas turbine engine having curved and offset struts.
This patent application is currently assigned to SOLAR TURBINES INCORPORATED. The applicant listed for this patent is Javier Leonardo Frailich, Jiang Luo, Christopher Zdzislaw Twardochleb. Invention is credited to Javier Leonardo Frailich, Jiang Luo, Christopher Zdzislaw Twardochleb.
Application Number | 20140026999 13/558161 |
Document ID | / |
Family ID | 49993704 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140026999 |
Kind Code |
A1 |
Frailich; Javier Leonardo ;
et al. |
January 30, 2014 |
EXHAUST DIFFUSER FOR A GAS TURBINE ENGINE HAVING CURVED AND OFFSET
STRUTS
Abstract
An exhaust diffuser having an outer turbine mounting interface,
an outer exhaust collector mounting interface, an outer diffuser
wall extending between the outer turbine mounting interface and the
outer exhaust collector mounting interface, an inner turbine
mounting interface, an inner exhaust collector mounting interface,
an inner diffuser wall extending between the inner turbine mounting
interface and the inner exhaust collector mounting interface, and a
plurality of struts circumferentially distributed around the center
axis and extending between the outer diffuser wall and the inner
diffuser wall, wherein each of the plurality of struts is radially
curved between the diffuser flow outer wall and the diffuser flow
inner wall, respectively, and wherein the termination points of
each strut is outer wall interface are radially offset from each
other.
Inventors: |
Frailich; Javier Leonardo;
(Chula Vista, CA) ; Twardochleb; Christopher
Zdzislaw; (Alpine, CA) ; Luo; Jiang; (San
Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Frailich; Javier Leonardo
Twardochleb; Christopher Zdzislaw
Luo; Jiang |
Chula Vista
Alpine
San Diego |
CA
CA
CA |
US
US
US |
|
|
Assignee: |
SOLAR TURBINES INCORPORATED
San Diego
CA
|
Family ID: |
49993704 |
Appl. No.: |
13/558161 |
Filed: |
July 25, 2012 |
Current U.S.
Class: |
138/39 |
Current CPC
Class: |
F01D 25/162 20130101;
F01D 25/30 20130101; F05D 2250/15 20130101 |
Class at
Publication: |
138/39 |
International
Class: |
F15D 1/04 20060101
F15D001/04 |
Claims
1. An exhaust diffuser for a gas turbine engine, the exhaust
diffuser comprising: an outer turbine mounting interface; an outer
exhaust collector mounting interface; an outer diffuser wall
extending between the outer turbine mounting interface and the
outer exhaust collector mounting interface, the outer diffuser wall
having a center axis; an inner turbine mounting interface; an inner
exhaust collector mounting interface; an inner diffuser wall
extending between the inner turbine mounting interface and the
inner exhaust collector mounting interface, the inner diffuser wall
coaxial with the outer diffuser wall; and a plurality of struts
circumferentially distributed around the center axis and extending
between the outer diffuser wall and the inner diffuser wall, each
of the plurality of struts joined to the outer diffuser wall at an
outer wall interface and joined to the inner diffuser wall at an
inner wall interface, wherein each of the plurality of struts is
radially curved between the outer wall interface and the inner wall
interface, respectively, and wherein each outer wall interface is
radially offset from its respective inner wall interface.
2. The exhaust diffuser of claim 1, wherein each of the plurality
of struts meets the inner diffuser wall at its respective inner
wall interface at a strut inner angle; and wherein the strut inner
angle is not zero degrees.
3. The exhaust diffuser of claim 2, wherein the strut inner angle
is between 20 degrees and 40 degrees.
4. The exhaust diffuser of claim 2, wherein each of the plurality
of struts meets the outer diffuser wall at its respective outer
wall interface at a strut outer angle; and wherein the strut outer
angle is between 10 degrees and minus 10 degrees.
5. The exhaust diffuser of claim 2, wherein each of the radially
curved plurality of struts has a convex side and a concave side;
and wherein each convex side faces against the direction of
residual swirl and each concave side faces in the direction of
residual swirl.
6. The exhaust diffuser of claim 1, wherein the plurality of struts
number six or fewer.
7. The exhaust diffuser of claim 1, wherein the outer diffuser wall
has a first axial length; wherein the inner diffuser wall has a
second axial length, the second axial length greater than the first
axial length; wherein the inner turbine mounting interface has a
first diameter; wherein the inner exhaust collector mounting
interface has a second diameter, the second diameter greater than
the first diameter; and wherein the exhaust diffuser is configured
to receive exhaust gas in a predominantly axial flow, impart a
radial direction to the exhaust gas, and transmit a predominantly
radial flow.
8. The exhaust diffuser of claim 1, wherein at least the outer
diffuser wall, the inner diffuser wall, and the plurality of struts
are formed together as a single unit from a single material.
9. The exhaust diffuser of claim 8, wherein at least the outer
diffuser wall, the inner diffuser wall, and the plurality of struts
are cast as a single investment casting.
10. A gas turbine engine having a center axis and a direction of
residual swirl, the gas turbine engine comprising: a turbine
including an outer turbine diffuser mounting flange; and an exhaust
diffuser including an outer turbine mounting interface, the outer
turbine mounting interface mechanically coupled to the outer
turbine diffuser mounting flange, an outer exhaust collector
mounting interface, an outer diffuser wall extending between the
outer turbine mounting interface and the outer exhaust collector
mounting interface, the outer diffuser wall having a center axis,
an inner turbine mounting interface, an inner exhaust collector
mounting interface, an inner diffuser wall extending between the
inner turbine mounting interface and the inner exhaust collector
mounting interface, the inner diffuser wall coaxial with the outer
diffuser wall, and a plurality of struts circumferentially
distributed around the center axis and extending between the outer
diffuser wall and the inner diffuser wall, each of the plurality of
struts joined to the outer diffuser wall at an outer wall interface
and joined to the inner diffuser wall at an inner wall interface,
wherein each of the plurality of struts is radially curved between
the outer wall interface and the inner wall interface,
respectively, and wherein each outer wall interface is radially
offset from its respective inner wall interface.
11. The gas turbine engine of claim 10, wherein each of the
plurality of struts meets the inner diffuser wall at its respective
inner wall interface at a strut inner angle measured from normal to
the inner diffuser wall and measured in the direction of residual
swirl; and wherein the strut inner angle is not zero degrees.
12. The gas turbine engine of claim 11, wherein the strut inner
angle is between 20 degrees and 40 degrees.
13. The gas turbine engine of claim 11, wherein each of the
plurality of struts meets the outer diffuser wall at its respective
outer wall interface at a strut outer angle measured from normal to
the outer diffuser wall and measured in the direction of residual
swirl; and wherein the strut outer angle is between 10 degrees and
minus 10 degrees, but not zero degrees.
14. The gas turbine engine of claim 11, wherein each of the
radially curved plurality of struts has a convex side and a concave
side; and wherein each convex side faces against the direction of
residual swirl and each concave side faces in the direction of
residual swirl.
15. The gas turbine engine of claim 10, wherein the plurality of
struts number six or fewer.
16. The gas turbine engine of claim 10, wherein the outer diffuser
wall includes a first axial length; wherein the inner diffuser wall
includes a second axial length, the second axial length greater
than the first axial length; wherein the inner turbine mounting
interface includes a first diameter; wherein the inner exhaust
collector mounting interface includes a second diameter, the second
diameter greater than the first diameter; and wherein the exhaust
diffuser receives exhaust gas in a predominantly axial flow,
imparts a radial component to the exhaust gas, and transmits a
predominantly radial flow.
17. The gas turbine engine of claim 10, wherein at least the outer
diffuser wall, the inner diffuser wall, and the plurality of struts
are formed together as a single unit from a single material.
19. The gas turbine engine of claim 17, wherein at least the outer
diffuser wall, the inner diffuser wall, and the plurality of struts
are cast as a single investment casting.
Description
TECHNICAL FIELD
[0001] The present disclosure generally pertains to gas turbine
engines, and is more particularly directed toward a gas turbine
exhaust diffuser.
BACKGROUND
[0002] A gas turbine engine generates high-temperature
high-velocity exhaust gas. The kinetic energy in the exhaust gas is
slowed and converted to static pressure by a diffuser before it is
released to the atmosphere. Components subjected to hot exhaust gas
may experience thermal expansion. Thermal expansion of fixed
structures may result in thermal cycling. In addition, being fixed,
even modest thermal expansion may result in interface stresses that
invite the design of stronger, often larger structures. The exhaust
diffuser serves to reduce the speed of the exhaust flow and hence
recovers static pressure along its flow path. Because of pressure
recovery in the diffuser, the turbine inlet-to-exit pressure ratio
is increased, resulting in higher power and efficiency.
[0003] Presently, U.S. Pat. App. Pub. No. 2011/00020166 to
Hashimoto et al. describes an axial gas turbine exhaust diffuser
having a plurality of strut covers that form sealed cooling
chambers. The axial gas turbine exhaust diffuser is located between
an outer casing wall and an inner bearing case. Hashimoto et al.
further describes a plurality of support struts extending between
the outer casing and the inner bearing casing, passing through the
sealed strut covers and cooling chambers of the exhaust diffuser,
wherein the struts include rounded ends and are coupled to a
tubular interface at the inner bearing case, and a tangential
direction, such that the inner bearing may rotate relative to the
center axis. Relative to expansion and contraction of the struts,
one end side and the other end side of the partition wall
supporting member are movably provided relative to the extending
direction of the struts, and the partition wall follows the
expansion and contraction of the struts.
[0004] The present disclosure is directed toward overcoming one or
more of the problems discussed above as well as additional problems
discovered by the inventor.
SUMMARY OF THE DISCLOSURE
[0005] An exhaust diffuser for a gas turbine engine is disclosed
herein. The exhaust diffuser having an outer turbine mounting
interface, an outer exhaust collector mounting interface, an outer
diffuser wall extending between the outer turbine mounting
interface and the outer exhaust collector mounting interface, an
inner turbine mounting interface, an inner exhaust collector
mounting interface, an inner diffuser wall extending between the
inner turbine mounting interface and the inner exhaust collector
mounting interface, and a plurality of struts circumferentially
distributed around the center axis and extending between the outer
diffuser wall and the inner diffuser wall. Each of the plurality of
struts is joined to the outer diffuser wall at an outer wall
interface and joined to the inner diffuser wall at an inner wall
interface. Each of the plurality of struts is radially curved
between the outer wall interface and the inner wall interface,
respectively. Each outer wall interface is radially offset from its
respective inner wall interface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic illustration of an exemplary gas
turbine engine.
[0007] FIG. 2 is an axial view of a gas turbine engine exhaust
diffuser.
[0008] FIG. 3 is a cutaway side view of the gas turbine engine
exhaust diffuser of FIG. 2, taken along line 3-3 of FIG. 2.
DETAILED DESCRIPTION
[0009] FIG. 1 is a schematic illustration of an exemplary
industrial gas turbine engine. Some of the surfaces have been left
out or exaggerated (here and in other figures) for clarity and ease
of explanation. Also, the disclosure will generally reference a
center axis 95 of rotation of the gas turbine engine, which may be
generally defined by the longitudinal axis of its shaft 120
(supported by a plurality of bearing assemblies 150). The center
axis 95 may be common to or shared with various other engine
concentric components. All references to radial, axial, and
circumferential directions and measures refer to center axis 95,
unless specified otherwise, and terms such as "inner" and "outer"
generally indicate a lesser or greater radial distance from,
wherein a radial 96 may be in any direction perpendicular and
radiating outward from center axis 95.
[0010] Structurally, a gas turbine engine 100 includes an inlet
110, a gas producer or "compressor" 200, a combustor 300, a turbine
400, an exhaust 500, and a power output coupling 600. The
compressor 200 includes one or more compressor rotor assemblies
220. The combustor 300 includes one or more injectors 350 and
includes one or more combustion chambers 390. The turbine 400
includes one or more turbine rotor assemblies 420. The exhaust
includes an exhaust diffuser 520 and an exhaust collector 550.
[0011] Functionally, a gas (typically air 10) enters the inlet 110
as a "working fluid", and is compressed by the compressor 200. In
the compressor 200, the working fluid is compressed in an annular
flow path 115 by the series of compressor rotor assemblies 220. In
particular, the air 10 is compressed in numbered "stages", the
stages being associated with each compressor rotor assembly 220.
For example, "5th stage air" may be associated with the 5th
compressor rotor assembly 220 in the downstream or "aft"
direction--going from the inlet 110 towards the exhaust 500). Other
numbering/naming conventions may also be used. Stages are similarly
associated with each turbine rotor assembly 420
[0012] Once compressed air 10 leaves the compressor 200, it enters
the combustor 300, where it is diffused and fuel 20 is added. Air
10 and fuel 20 are injected into the combustion chamber 390 via
injector 350 and ignited. After the combustion reaction, energy is
then extracted from the combusted fuel/air mixture via the turbine
400 by each stage of the series of turbine rotor assemblies 420.
Exhaust gas 90 may then be diffused in exhaust diffuser 520 and
collected, redirected, and exit the system via an exhaust collector
550. Exhaust gas 90 may also be further processed (e.g., to reduce
harmful emissions, and/or to recover heat from the exhaust gas
90).
[0013] One or more of the above components (or their subcomponents)
may be made from stainless steel and/or durable, high temperature
materials known as "superalloys". A superalloy, or high-performance
alloy, is an alloy that exhibits excellent mechanical strength and
creep resistance at high temperatures, good surface stability, and
corrosion and oxidation resistance. Superalloys may include
materials such as HASTELLOY, INCONEL, WASPALOY, RENE alloys, HAYNES
alloys, INCOLOY, MP98T, TMS alloys, and CMSX single crystal
alloys.
[0014] FIG. 2 is an axial view of a gas turbine engine exhaust
diffuser. In particular, the exhaust diffuser 520 schematically
illustrated in FIG. 1 is shown here in greater detail, but in
isolation from the rest of gas turbine engine 100. In general,
exhaust diffuser 520 may be conceptualized as two concentric
structures (e.g., tubes), joined to each other via a plurality of
struts 527 circumferentially distributed around the center axis 95.
Here, the concentric structures include the outer diffuser wall 523
and the inner diffuser wall 526. Accordingly, the inner diffuser
wall 526 may generally have a smaller diameter than the outer
diffuser wall 523. Thus, together, the outer diffuser wall 523 and
the inner diffuser wall 526 may provide an annular exhaust flow
path 528 between the turbine 400 (FIG. 1) and the exhaust collector
550 (FIG. 1), interrupted by only the struts 527 themselves.
[0015] With regard to the plurality of struts 527, each strut 527
may extend between the outer diffuser wall 523 and the inner
diffuser wall 526. Each of the plurality of struts 527 may be
joined to the outer diffuser wall 523 at an outer wall interface
536 and joined to the inner diffuser wall 526 at an inner wall
interface 537, respectively.
[0016] Here, outer wall interface 536 and the inner wall interface
537 are merely descriptive of the location of the strut/wall
juncture, as opposed to the manner in which the components are
joined. For example, the outer diffuser wall 523, the inner
diffuser wall 526, and strut 527 may be formed together as a single
unit from a single material (e.g., cast as a single investment
casting) or joined together as individually made components (e.g.,
welded or fastened together otherwise).
[0017] Independent of the method of forming their juncture at the
outer wall interface 536 and the inner wall interface 537, the
struts 527 form a structural part of the exhaust diffuser 520,
positioning and supporting the outer diffuser wall 523 and the
inner diffuser wall 526 relative to each other, while providing
passageways for the hot exhaust gas 90 to pass through. In this
way, exhaust diffuser 520 becomes less complex from a maintenance
stand point, and may be removed and replaced as a single unit.
[0018] In addition, the exhaust diffuser 520 may include features
that may mitigate losses associated with the presence of each strut
527 in the flow stream, while still positioning and supporting the
outer diffuser wall 523 and the inner diffuser wall 526. According
to one embodiment, the total number of struts 527 may be limited to
six, thus mitigating losses and airflow disturbances associated
with the cumulative presence of a greater number of struts 527.
According to another embodiment, and as illustrated, each strut 527
may be placed directly in the stream of exhaust gas 90, without any
external ducting or shielding. For example, each strut 527 may be
made of a material, such as a corrosion resistant steel or
superalloy, selected for both its structural strength as well as
its resistance to exposure to the hot exhaust gas 90 leaving the
turbine 400 (FIG. 1). According to yet another embodiment, each
strut 527 may include an aerodynamic profile in order to further
mitigate profile losses associated with the presence of each strut
527 directly in the stream of exhaust gas 90. For example, each
strut 527 may include a rounded leading edge, an axially-symmetric
body, a tapered trailing edge, and a zero or near zero angle of
attack, relative to the flow of the exhaust gas 90.
[0019] As illustrated, each of the plurality of struts 527 may be
radially curved between its respective outer wall interface 536 and
its inner wall interface 537. In particular, when viewed from the
axial direction (here, looking downstream), each strut 527 may form
a curved shape, i.e., without inflection points in a plane
perpendicular to the center axis 95. The radial curvature of the
strut 527 may be such that at least a portion of the stresses local
to the outer wall interface 536 and/or the inner wall interface 537
due to thermal expansion of the strut 527 are taken up within the
strut 527. For example, had strut 527 been without any radial
curvature (i.e. a straight line between the outer wall interface
536 and the inner wall interface 537), stresses caused by thermal
expansion of the strut 527 could be efficiently transferred
directly to the outer wall interface 536 and/or the inner wall
interface 537. However, by including at least a minimum curvature
to the strut 527, at least some of those stresses may be
distributed into the curved region, mitigating interface stresses
of thermal expansion. According to one embodiment, the curvature of
strut 527 may be defined by a second order polynomial tailored to
the particular dimensions and thermal and performance
specifications of the exhaust diffuser 520. For example, the
curvature of strut 527 may be defined by the equation Y=1.3975X
2+3.2802X+6.4951.
[0020] Also, having a simple curvature as described above, the
radial curve of each strut 527 may include a convex side 545 and a
concave side 546. As illustrated, the convex side 545 may include
supplemental support structure at or near its base, i.e., at both
its outer wall interface 536 and its inner wall interface 537. It
is understood, however, that with regard to describing the radial
curvature of the strut 527, the additional shape of said
supplemental support structure may be disregarded. Furthermore, the
radial curvature of the strut 527 may be measured by the curvature
of its concave side 546 since, at both its outer wall interface 536
and its inner wall interface 537, the radial curvature of the strut
527 remains substantially the same as the curvature of its concave
side 546. This may be desirable, for example, where measurement
through a centerline of the strut 527 is undesired or
inconvenient.
[0021] According to one embodiment, the radial curvature of strut
527 may vary along the path between the outer wall interface 536
and the inner wall interface 537. In particular, the bend radius of
the strut 527 at one point may be different from the bend radius of
the strut 527 at another point. For example, the strut 527 may be
substantially straight at or near its outer wall interface 536, but
smoothly transition to its maximum curvature at or near its inner
wall interface 537. In addition, the radial curvature of strut 527
may be used to set a strut outer angle 541 and or a strut inner
angle 542, as discussed further below.
[0022] According to one embodiment, the radial curvature of the
strut 527 may be oriented relative to the direction of residual
swirl 97. After the last turbine stage, in addition to having a
predominantly axial flow, exhaust gas 90 may have a circumferential
velocity component or "residual swirl". Here direction of residual
swirl 97 is represented as counter clockwise (CCW). It is
understood that residual swirl of the exhaust gas 90 may be
nominal, in the opposite direction, and/or variable.
[0023] According to one embodiment the strut 527 may be oriented
such that its convex side 545 faces against the direction of
residual swirl 97, and its concave side 546 faces in the direction
of residual swirl 97. It is understood that the CCW direction of
residual swirl 97 is merely exemplary and not limiting to the
disclosure. For example, according to this embodiment, had the
direction of residual swirl 97 been CW, the strut 527 could be
flipped about a radial 96 passing though either end point (outer
wall interface 536 or inner wall interface 537 outer wall interface
536 and the inner wall interface 537).
[0024] Also as illustrated, each outer wall interface 536 may be
radially offset from its respective inner wall interface 537. In
particular, when viewed from the axial direction as shown, the
outer wall interface 536 may reside on a different radial 96 than
its respective inner wall interface 537. In this way, thermal
expansion of the strut 527 during engine operation may tangentially
translate loads that would otherwise be normal to the outer
diffuser wall 523 and the inner diffuser wall 526 into the outer
diffuser wall 523 and the inner diffuser wall 526 in a
circumferential direction. Thus, thermal expansion interface
stresses may be converted to rotation, torsion, and/or distributed
across larger structures such as their respective mounting
interfaces.
[0025] According to one embodiment, the strut 527 may meet the
outer diffuser wall 523 at a normal angle or at a non-normal angle
(i.e., non-perpendicular to a tangent plane of the outer diffuser
wall 523). In particular, strut 527 may interface with the diffuser
flow outer wall 526 at a strut outer angle 541 set such that the
thermal expansion of strut 527 during engine operation will result
in sufficient translation/transfer of interface stresses at its
outer wall interface 536 to the outer diffuser wall 523, which may
be taken up by its material properties as a minor torque applied
between the outer diffuser wall 523 and the inner diffuser wall
526. For example, according to one embodiment, the strut 527 may
interface with the outer diffuser wall 523 at a strut outer angle
541 within the range of plus 10 degrees to minus 10 degrees from
normal.
[0026] As discussed above, the radial curvature of strut 527 may be
coordinated/varied with the outer diffuser wall 523 to provide or
set the desired strut outer angle 541. In addition, as discussed
below, where interface stress is sufficiently taken up elsewhere,
the strut outer angle 541 may approach normal, or zero degrees.
Here, the strut outer angle 541 is represented as an extrapolation
of the general direction of the strut 527 at its outer wall
interface 536. The general direction may be taken through the
middle of the strut 527, neglecting any additional structures
(e.g., fillets or chamfers) local to the outer wall interface 536.
Alternately, as can be seen, the strut outer angle 541 may be
conveniently approximated by the tangent to the curve of the strut
527 on its concave side 546, also neglecting any additional
structure local to the outer wall interface 536.
[0027] According to one embodiment, the strut 527 may meet the
inner diffuser wall 526 at a non-normal angle (i.e.,
non-perpendicular to a tangent plane of the inner diffuser wall
526). In particular, strut 527 may interface with the inner
diffuser wall 526 at a strut inner angle 542 such that the thermal
expansion of strut 527 during engine operation will result in
sufficient translation/transfer of interface stresses at its inner
wall interface 537 to the inner diffuser wall 526, which may be
taken up by material properties as a minor torque applied between
the outer diffuser wall 523 and the inner diffuser wall 526.
[0028] Unlike the strut outer angle 541, the strut inner angle 542
may significantly depart a normal (perpendicular) angle. For
example, according to one embodiment, the strut 527 may interface
with the inner diffuser wall 526 at a strut inner angle 542 within
the range of 20 degrees to 40 degrees from normal. As above, the
strut inner angle 542 is represented as an extrapolation of the
general direction of the strut 527 at its inner wall interface 537.
The general direction may be taken through the middle of the strut
527, neglecting any additional structures local to the outer wall
interface 536. Alternately, as can be seen, the strut outer angle
541 may be conveniently approximated by the tangent to the curve of
the strut 527 on its concave side 546, also neglecting any
additional structures local to the inner wall interface 537.
[0029] In addition, and similar to its radial curvature, a strut
inner angle 542 may take in account the direction of residual swirl
97. In particular, the strut 527 may interface with the inner
diffuser wall 526 at a strut inner angle 542 within the range of 20
degrees to 40 degrees from normal as measured in the direction
against the direction of residual swirl 97 (here in the CW
direction). As discussed above, the radial curvature of strut 527
may be coordinated/varied with the inner diffuser wall 526 to
provide or set the desired strut inner angle 542.
[0030] FIG. 3 is a cutaway side view of a gas turbine engine
exhaust diffuser as taken along line 3-3 of FIG. 2, with the
addition of partial views of its mounting components for contextual
purposes. As discussed above, exhaust diffuser 520 may
conceptualized as two concentric structures (e.g., tubes), joined
to each other via a plurality of struts 527. Exhaust diffuser 520
may be in axial configuration, a radial configuration, or a
combination thereof. In the currently illustrated radial
configuration, exhaust diffuser 520 will generally have a much
shorter axial length, as a whole, than if it were in an axial
diffuser configuration.
[0031] As illustrated, exhaust diffuser 520 receives hot exhaust
gas 90 from the turbine 400 in a predominantly axial flow 534
(i.e., in the direction of the center axis 95), imparts a radial
component (i.e., in the direction of a radial 96 off the center
axis 95) to the exhaust gas 90, and transmits a predominantly
radial flow 535 or outward flow downstream into the exhaust
collector 550. Exhaust collector 550 may then "collect" the exhaust
gas 90 and direct it away in a single, convenient direction.
Notably, since the hot exhaust gas 90 is largely redirected by its
inner diffuser wall 526 in the illustrated configuration, transfer
of heat and impingement force to the inner diffuser wall 526 may be
greater than in an axial diffuser configuration.
[0032] With regard to the outer structure discussed above, exhaust
diffuser 520 may include an outer turbine mounting interface 521,
an outer exhaust collector mounting interface 522, and the outer
diffuser wall 523. The outer diffuser wall 523 may be generally
tubular in shape, and extend between the outer turbine mounting
interface 521 and the outer exhaust collector mounting interface
522.
[0033] With regard to the inner structure, the exhaust diffuser 520
may include an inner turbine mounting interface 524, an inner
exhaust collector mounting interface 525, and the inner diffuser
wall 526. The inner diffuser wall 526 may also be generally tubular
in shape (here, with a flared end), and extend between its inner
turbine mounting interface 524 and inner exhaust collector mounting
interface 525.
[0034] Being a radial diffuser, features of the inner diffuser wall
526 may differ significantly from those of outer diffuser wall 523.
In particular, the axial length 530 of the inner diffuser wall 526
may be greater than the axial length 533 of the outer diffuser wall
523. The axial length of each wall may conveniently be measured
from interfacing surfaces of each end. The additional length
providing for a transitional area where exhaust gas 90 changes
direction from a predominantly axial flow 534 to a predominantly
radial flow 535. Accordingly, the inner diffuser wall 526 may curve
outward and provide the radial component to the exhaust gas 90.
[0035] Also, the diameter 532 of the inner exhaust collector
mounting interface 525 may be greater than the diameter 531 of the
inner turbine mounting interface 524. Moreover, the diameter 532 of
the inner exhaust collector mounting interface 525 may be greater
than or equal to the diameter 538 of the outer turbine mounting
interface 521. Referring also to FIG. 2, the diameter of each
interface may conveniently be measured through the center of its
respective fasteners. Alternately, the diameter of each interface
may conveniently be measured at its outermost radial distance. The
flared out inner diffuser wall 526 cumulating with the increased
diameter 532 at its inner exhaust collector mounting interface 525
provides for the inner diffuser wall 526 to impart redirective
forces on the exhaust gas 90, changing its flow direction and to
transmit a predominately radial flow in 360 degrees to the exhaust
collector 550.
[0036] Upon installation, both the inner and outer diffuser walls
526, 523 may be mechanically and fluidly coupled to the turbine 400
and the exhaust collector 550 via their respective mounting
interfaces. In particular and as illustrated here and in FIG. 2,
the outer turbine mounting interface 521 and the outer exhaust
collector mounting interface 522 may each include a generally
circular shaped ring that is part of (e.g., machined into) or
joined to the outer diffuser wall 523. Each ring may include
fastening points such as a plurality of bolt holes
circumferentially distributed around each ring. Accordingly, both
outer interface rings may then be bolted to a mating interface,
such as an outer turbine diffuser mounting flange 491 or an Outer
exhaust collector diffuser mounting flange 591.
[0037] Also as illustrated, the inner turbine mounting interface
524 and the inner exhaust collector mounting interface 525 may each
include a circular ring that is part of (e.g., machined into) or
joined to the inner diffuser wall 526. Each ring may include
fastening points such as a plurality of bolt holes
circumferentially distributed around each ring. Accordingly, both
interface rings may then be bolted to a mating interface, such as
an inner turbine diffuser mounting flange 492 or an inner exhaust
collector diffuser mount 592.
INDUSTRIAL APPLICABILITY
[0038] The present disclosure generally provides an exhaust
diffuser, and a gas turbine engine having an exhaust diffuser. As
applied, gas turbine engines, and thus their components, may be
suited for any number of industrial applications, such as, but not
limited to, various aspects of the oil and natural gas industry
(including transmission, gathering, storage, withdrawal, and
lifting of oil and natural gas), power generation industry,
aerospace and transportation industry, to name a few examples.
[0039] The disclosed exhaust diffuser is generally applicable to
any gas turbine engine having an exhaust diffuser. This includes
radial flow exhaust diffusers, axial flow exhaust diffusers, and
hybrids thereof. As described, the exhaust diffuser is particularly
suited for applications calling for a radial gas diffuser, which
may have shorter axial lengths and strong flow turning.
[0040] Additionally, the disclosed exhaust diffuser is particularly
applicable to the use, operation, maintenance, repair, and
improvement of gas turbine engines. Specifically, the exhaust
diffuser may be suited for the design, manufacture, test, repair,
overhaul, and improvement of exhaust diffusers where relief of
strut thermal expansion would be desirable. For example, compared
to an exhaust diffuser having many radial struts that are
interfaced normal to the inner and outer diffuser walls, interface
stresses associated with thermal expansion of the struts may be
mitigated by being distributed into the curvature of the struts
and/or being translated from a shear and normal force taken up at
the strut interface, to a rotational force taken up across the
exhaust diffuser interfaces (or otherwise). This is beneficial as
struts, having a lower mass and being placed directly in the
exhaust stream, may heat up and thermally expand before its
surrounding casing.
[0041] In order to improve efficiency, decrease maintenance, and
lower costs, embodiments of the presently disclosed exhaust
diffuser may be used on exhaust systems at any stage of the gas
turbine engine's life, from first manufacture and prototyping to
end of life. In addition, the simplified design, with integrated
struts, may outperform and be easier to build and maintain that
more complicated and bulky actively cooled exhaust diffuser
systems. Accordingly, the disclosed exhaust diffuser may be used as
an enhancement to existing gas turbine engine exhaust diffuser, as
a preventative measure, or even in response to an event. This is
particularly true as the presently disclosed exhaust diffuser may
conveniently include identical mounting interfaces to an older type
of exhaust diffuser.
[0042] Although this invention has been shown and described with
respect to a detailed embodiment thereof, it will be understood by
those skilled in the art that various changes in form and detail
thereof may be made without departing from the spirit and scope of
the claimed invention. Accordingly, the preceding detailed
description is merely exemplary in nature and is not intended to
limit the invention or the application and uses of the invention.
In particular, the described embodiments are not limited to use in
conjunction with a particular type of gas turbine engine. For
example, the described embodiments may be applied to stationary or
motive gas turbine engines, or any variant thereof. It will be
recognized that in some instances the described embodiments may
also be used in other machines that also produce high temperature,
high speed exhaust air. Furthermore, there is no intention to be
bound by any theory presented in any preceding section. It is also
understood that the illustrations may include exaggerated
dimensions and graphical representation to better illustrate the
referenced items shown, and are not consider limiting unless
expressly stated as such.
* * * * *